The present invention generally relates to material displacement apparatus and, in a preferred embodiment thereof, more particularly relates to a specially designed rotary lock structure for releasably holding a replaceable earth excavating tooth point on a nose portion of an associated adapter structure.
A variety of types of material displacement apparatus, such as earth working structures, are typically provided with replaceable portions that are removably carried by larger base structures and come into abrasive wearing contact with the material being displaced. For example, excavating tooth assemblies provided on digging such as excavating buckets or the like typically comprise a relatively massive adapter portion which is suitably anchored to the forward bucket lip and has a reduced cross-section, forwardly projecting nose portion, and a replaceable tooth point having formed through a rear end thereof a pocket opening that releasably receives the adapter nose. The removability of the tooth point advantageously permits the more massive adapter to have a substantially longer operating life than if the point was an integral portion thereof.
To captively retain the tooth point on the adapter nose, aligned transverse openings are formed through these interengageable elements adjacent the rear end of the point, and a suitable connector structure is forcibly driven into and retained within the openings to releasably anchor the replaceable tooth point on its associated adapter nose portion. These connector structures adapted to be driven into the aligned tooth point and adapter nose openings typically come in two primary forms--(1) wedge and spool connector sets, and (2) flex pin connectors.
A wedge and spool connector set comprises a tapered spool portion which is initially placed in the aligned tooth and adapter openings, and a tapered wedge portion which is subsequently driven into the openings, against he spool portion, to jam the structure in place within the openings in a manner exerting high rigid retention forces on he interior opening surfaces and press the nose portion into a tight fitting engagement with the interior surface of the tooth socket.
Very high drive-in and knock-out forces are required to insert and later remove the steel wedge and typically require a two man effort to pound the wedge in and out--one man holding a removal tool against an end of the wedge, and the other man pounding on the removal tool with a sledge hammer. The drive-in and knock-out forces, of course, increase with the size of the tooth/adapter nose assembly involved. This creates a safety hazard due to the possibility of flying metal slivers and/or the second man hitting the first man instead of the removal tool with the sledge hammer. Additionally, wear between the tooth/adapter nose assembly surface interface during excavation use of the tooth tends to loosen the original tight fit of the wedge/spool structure within the tooth and adapter nose openings, thereby permitting the wedge/spool structure to fall out of the openings and thus permitting the tooth to fall off the adapter nose.
Flex pin connector structures, on the other hand, typically comprise two elongated metal members held in a spaced apart, side-by-side orientation by an elastomeric material bonded therebetween. The flex pin structure must be longitudinally driven into the tooth and adapter nose openings to cause the elastomeric material to be compressed and resiliently force the metal members against the nose and tooth opening surfaces to retain the connector structure in place within the openings and resiliently press the adapter nose portion into tight fitting engagement with the interior surface of the tooth socket. This creates essentially the same potential safety hazards as arise when a metal wedge member is being driven into the tooth and adapter nose openings as previously described herein. Subsequently, of course, the flex pin structure must be pounded out of the tooth and adapter openings.
Conventionally constructed flex pin structures also have other disadvantages and limitations. For example, compared to wedge/spool structures they have a substantially lower in-place retention force. This is due to the fact that the elastomeric flex pin portion, as the flex pin is being driven into place within the tooth/adapter nose assembly, must be compressed more than when it reaches its installed position within the assembly. Thus, the elastomeric element partially "relaxes" when it reaches its installed position and cannot exert its full available resilient retention force on the tooth and adapter nose surfaces.
Moreover, in conventionally configured flex pin structures, the retention of the flex pin structure within the tooth/adapter nose assembly is dependent upon maintaining a certain minimum resilient force by the elastomeric element on an interior surface portion of the tooth/adapter nose assembly. When internal assembly surface wear progresses to a certain point the connector can fall out because this resilient force is no longer large enough. It can be seen from the foregoing that it would be desirable to provide improved excavating tooth connector apparatus that eliminates or at least substantially reduces the above-mentioned problems, limitations and disadvantages commonly associated with conventional excavating tooth and other material displacement equipment connector apparatus of the general type described above. It is accordingly an object of the present invention to provide such improved connector apparatus.